An Effective Biomass for the Adsorption of Methylene Blue Dye and Treatment of River Water

Neolamarckia cadamba leaves were used as an adsorbent for methylene blue removal as well as for the reduction in the water quality parameters of the sewage belts of Yamuna River in Allahabad, Uttar Pradesh, India. A variety of water quality parameters were assessed, including chemical oxygen demand, biological oxygen demand, total dissolved solids, conductivity, hardness, pH, and temperature. A great deal of degradation in the water quality parameters collected from three locations within the Yamuna River in Allahabad, Uttar Pradesh, India, has been observed by treating with Neolamarckia cadamba leaves. The adsorption studies were carried out by the batch method, and the effect of various parameters such as contact time, pH, initial concentration, and temperature was assessed. The maximum removal of methylene blue was obtained at pH 5 after 120 minutes of equilibrium time. In addition to fitting the Langmuir isotherm most accurately, the adsorbent also followed pseudokinetics of the second order. The maximum monolayer adsorption capacity of used biomass was 101 mg/g using 50 mg/L methylene blue solution. It is evident from the thermodynamic data that the adsorption is exothermic. Also, the spontaneity of the interaction between adsorbent and adsorbate decreases with temperature. Energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy techniques were used to characterize the adsorbent. SEM images revealed that the biomass consisted of irregular spherical lumps with a porous structure, which provided effective adsorption sites. A chemical composition analysis of the biomass by EDAX shows that the chemical composition of oxygen and carbon decreases, whereas nitrogen’s chemical composition increases.

Green synthesis, characterization, application and functionality of nitrogen-doped MgO/graphene nanocomposite

A facile, feasible, and green synthesis via an electrochemical exfoliation process was applied to synthesize nitrogen-doped MgO/graphene nanocomposite (N-MgO/G). The N-MgO/G nanocomposite was characterized by several analytical techniques including X-ray photoelectron spectroscopy, X-ray powder diffraction, transmission electron microscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected area electron diffraction, and elemental mapping analysis. N-MgO/G nanocomposite was then applied to adsorb lead metal ions (Pb²⁺) from aqueous solutions. The N-MgO/G nanocomposite demonstrated a remarkably high Langmuir maximum adsorption capacity (294.12 mg/g) for Pb²⁺ ions under the optimum experimental conditions at a pH of 5.13, time of 35 min, dose of 0.025 g, the concentration of 400 mg/L, and a temperature of 36 °C. Adsorption kinetics results fitted with a pseudo-second-order model and a thermodynamic study showed that Pb²⁺ adsorption is an endothermic process. The practical application of N-MgO/G was also investigated to test its applicability in real water samples collected from different sources such as deionized water, tap water, wastewater, and river water.

The advantages of clay mineral modification methods for enhancing adsorption efficiency in wastewater treatment: a review

This review discusses the recent trends in the research over the last 30 years to use clay minerals in natural and modified forms for removing different toxic organic/inorganic pollutants. The natural and modified forms of clay minerals have an exceptional ability to remove different contaminants. However, the modification methods can improve the clay mineral adsorption properties that consequently increase more adsorption sites and functional groups to adsorb different environmental pollutants. This review shows the importance of modification methods and more extension of novel clay preparation based on nanotechnology which could raise the control of pollution. The syntheses of functionalized clays such as pillared clays and porous clay heterostructures introduce the new class of heterostructure materials with high adsorption capacity, capability, and selectivity. Due to the acceptable properties of heterostructure materials including high specific surface area, thermal and mechanical stability, and the existence of multifunctional groups to selective adsorption, this review collects more literature of research related to environmental protection issues. However, it is expected much attention to get a better understanding of the adsorption mechanism, regeneration, and recovery process of these materials.